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  OPERATION-2023 logbook, Contact: F.Wolff-Fabris, A.Galler, L.Samoylova, H.Sinn  Not logged in ELOG logo
Message ID: 351     Entry time: 22 Sep 2023, 00:56
Author: Jan Gruenert 
Group: PRC 
Subject: SA1 status 

As agreed beforehand, PRC and SPB/SFX re-assessed the SA1 EPS power limit based on actual performance, required number of pulses and rep rate, at the agreed SPB photon energy of 7 keV.
The actual lasing performance is on average 1.3 mJ / pulse at the current 7 keV.
Before the change, the assumed minimum pulse energy per requested bunch was set to 3.0 mJ in the Big Brother EPS power limit SA1, where we had set the remote power limit to 5 W.
To allow for the required 202 bunches at 0.5 MHz for SPB, I changed to an assumed minimum pulse energy per requested bunch of 2.2 mJ while maintaining the 5 W limit (rather than the inverse).
Maintaining in this way the 5 W limitation ensures that even if by human error during the shift change a high number of pulses would be requested at 5.5 keV, this could by no means damage the CRLs.

Additionally the SPB/SFX and the BKR operators were reminded about the safe procedure for the shift handover:
a) first the number of bunches has to be set to single bunch per train
b) then the wavelength could be changed
c) then the respective instrument would make sure that the beamline is in a safe state (e.g. CRL1 retracted) before a higher number of bunches would be requested (in particular at 5.5 keV).

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